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The frequency range of TMJ sounds.
S E Widmalm1, W J Williams, D Djurdjanovic
1Department of Biologic Sciences, School of Dentistry, University of Michigan, Ann Arbor, MI, USA. sew@umich.edu
Journal of Oral Rehabilitation
|March 13, 2003
Summary
Temporomandibular joint (TMJ) sounds may have higher frequencies than previously thought. Using ear canal microphones reveals higher TMJ sound frequencies compared to skin contact sensors.
Area of Science:
- Biomechanics
- Acoustics
- Otolaryngology
Background:
- Conflicting reports exist regarding the upper frequency limit of temporomandibular joint (TMJ) sounds, with some suggesting it is around 650 Hz.
- The transmission path of TMJ vibrations through head tissues and the recording methods used may influence the measured frequency spectrum.
Purpose of the Study:
- To test the hypothesis that TMJ sounds contain frequencies significantly above 650 Hz.
- To investigate the impact of recording methods (contact sensors vs. microphones) and transmission distance on TMJ sound frequency measurements.
Main Methods:
- Comparison of time-frequency distributions of 172 TMJ clickings from three subjects.
- Recordings were made using an ear canal microphone on the affected side, a skin contact transducer over the joint, and microphones in both ear canals.
Main Results:
- TMJ clickings recorded with an ear canal microphone on the affected side showed energy peaks significantly higher (117-1922 Hz) than those recorded with contact sensors (47-375 Hz).
- Frequencies recorded via ear canal microphones on the affected side were also significantly higher than those from the contralateral ear canal microphone (141-703 Hz).
Conclusions:
- TMJ sounds can possess frequencies well above the previously reported 650 Hz limit.
- Current recording methods, particularly contact sensors and recordings from the non-affected side, may underestimate the true high-frequency content of TMJ sounds. Further research using high-frequency vibration-capable methods is needed.